METHOD FOR HEAT-TREATING METAL TUBES OR PIPES FOR NUCLEAR POWER PLANT, BATCH-TYPE VACUUM HEAT TREATMENT FURNACE USED THEREFOR, AND METAL TUBES OR PIPES FOR NUCLEAR POWER PLANT HEAT-TREATED BY THE SAME

摘要

In a method for heat treating a metal tube or pipe for a nuclear power plant,the tube or pipe being accommodated in a batch-type vacuum heat treatmentfurnace,when the tube or pipe is laid down on and is subjected to heat treatment on apluralityof metal cross beams arranged along a longitudinal direction of the tube orpipe, it ispossible to suppress scratches to be formed on the outer surface of the tubeor pipeand attributable to heat treatment, and to reduce the discoloration on theouter surfaceof the tube or pipe by holding the tube or pipe and the metal cross beams inindirectcontact with each other by virtue of a heat resistant fabric having athickness of 0.1 to1.2 mm interposed in between. In this occasion, it is preferable to use ametal tubeor pipe having a composition consisting of, in mass%, C: 0.15% or less, Si:1.00% orless, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to40.0%, Ni:8.0 to 80.0%, Ti: 0.5% or less, Cu: 0.6% or less, Al: 0.5% or less, and N:0.20% orless, the balance being Fe and impurities.